package com.itheima.a05test;

import java.util.HashSet;
import java.util.Set;

public class A01_SetDemo1 {
    public static void main(String[] args) {
        Set<String> set=new HashSet<>();
        boolean s1=set.add("张三");
        boolean s2=set.add("张三");
        System.out.println(s1);
        System.out.println(s2);
        System.out.println(set);
    }
}
